I have been trying to be creative and to rethink what may meet your needs. I think that you may find more joy looking to the pro industry for what you want. This is really me thinking aloud rather then any sort of recommendation but I think some decent pro active PA speakers plus a bluetooth receiver may go most of the way to serve you.
So here is a pair of Electrovoice active speakers . I have very fond memories of using EV for PA use back in the seventies. The folded horns we were using ( Sentinels?) sounded great for that application. They have a whole range of speakers so this is just an example. There are less and more costly ones:
There is no weatherproof spec but if it doesn’t meet that requirement I would bet that EV make 'em .
To pick up your Bluetooth signal from your source there is , say :
https://www.denonpro.com/index.php/products/view/dn-200br
It looks small enough to take indoors at the end of the day and/or easy enough to put in some plastic sheeting or other prophylactic against any rain. Only a small length of wire to the speaker is then needed.
As I say I am just thinking aloud and there are likely to be other products to do something similar.